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<h4 class="subsection" id="Elif-1"><span>4.2.5 Elif<a class="copiable-link" href="#Elif-1"> &para;</a></span></h4>

<a class="index-entry-id" id="index-_0023elif"></a>
<p>One common case of nested conditionals is used to check for more than two
possible alternatives.  For example, you might have
</p>
<div class="example smallexample">
<pre class="example-preformatted">#if X == 1
...
#else /* X != 1 */
#if X == 2
...
#else /* X != 2 */
...
#endif /* X != 2 */
#endif /* X != 1 */
</pre></div>

<p>Another conditional directive, &lsquo;<samp class="samp">#elif</samp>&rsquo;, allows this to be
abbreviated as follows:
</p>
<div class="example smallexample">
<pre class="example-preformatted">#if X == 1
...
#elif X == 2
...
#else /* X != 2 and X != 1*/
...
#endif /* X != 2 and X != 1*/
</pre></div>

<p>&lsquo;<samp class="samp">#elif</samp>&rsquo; stands for &ldquo;else if&rdquo;.  Like &lsquo;<samp class="samp">#else</samp>&rsquo;, it goes in the
middle of a conditional group and subdivides it; it does not require a
matching &lsquo;<samp class="samp">#endif</samp>&rsquo; of its own.  Like &lsquo;<samp class="samp">#if</samp>&rsquo;, the &lsquo;<samp class="samp">#elif</samp>&rsquo;
directive includes an expression to be tested.  The text following the
&lsquo;<samp class="samp">#elif</samp>&rsquo; is processed only if the original &lsquo;<samp class="samp">#if</samp>&rsquo;-condition
failed and the &lsquo;<samp class="samp">#elif</samp>&rsquo; condition succeeds.
</p>
<p>More than one &lsquo;<samp class="samp">#elif</samp>&rsquo; can go in the same conditional group.  Then
the text after each &lsquo;<samp class="samp">#elif</samp>&rsquo; is processed only if the &lsquo;<samp class="samp">#elif</samp>&rsquo;
condition succeeds after the original &lsquo;<samp class="samp">#if</samp>&rsquo; and all previous
&lsquo;<samp class="samp">#elif</samp>&rsquo; directives within it have failed.
</p>
<p>&lsquo;<samp class="samp">#else</samp>&rsquo; is allowed after any number of &lsquo;<samp class="samp">#elif</samp>&rsquo; directives, but
&lsquo;<samp class="samp">#elif</samp>&rsquo; may not follow &lsquo;<samp class="samp">#else</samp>&rsquo;.
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